// Not owned; provides operations on Tensors which are currently only
  // available in language bindings (e.g. Python).
  const VSpace<Gradient, BackwardFunction, TapeTensor>& vspace_;

  // Decides if tangents are vectorized or not
  bool use_batch_;

  struct AccumulatorCallState {
    AccumulatorCallState(
        GradientTape<Gradient, BackwardFunction, TapeTensor>* backward_tape,
        bool accumulating)

                                           const char* path,
                                           TF_TransactionToken** token,
                                           TF_Status* status);

  /// Decodes transaction token in `token` to human readable format for
  /// debugging.
  ///
  /// A new `char*` buffer must be allocated by this method. Core TensorFlow